The correct answer is: A. PDC
PDC (Personal Digital Cellular) is a second-generation digital cellular telecommunications system developed in Japan. It was the first digital cellular system to be deployed in Japan, and it was also the first digital cellular system to be deployed in the world using time-division multiple access (TDMA).
USDC (United States Digital Cellular) is a second-generation digital cellular telecommunications system developed in the United States. It was the first digital cellular system to be deployed in the United States, and it was also the first digital cellular system to be deployed in the world using code-division multiple access (CDMA).
IS-95 (cdmaOne) is a second-generation digital cellular telecommunications system developed in the United States. It was the first digital cellular system to be deployed in the world using CDMA.
GSM (Global System for Mobile Communications) is a second-generation digital cellular telecommunications system developed in Europe. It is the most widely used digital cellular system in the world. GSM uses TDMA.
In conclusion, PDC is the only option that did not adopt digital TDMA for high capacity.